The first thing I do?
Um, probably start laughing in as ominous a way as possible. I need to work on my Ominous Laughter.
Past that? I'd ask for Switzerland's net worth to be delivered in my personal bank account or threaten to vaporize the remainder of the world's oil supplies with my Super Vaporizer of Doom that Kills and Maims.
Then I'd research sustainable alternatives to fossil fuels and vat-grown meats and produce - and share none of it. I'd demand fealty from the world's petty governments in exchange for my wondrous technologies. Whoever subverts my gracious gifts into tools of war gets obliterated by yours truly. Anyone who denies Science and threatens innocents with ridiculous God-fearing nonsense is also up for grabs. The Mormons, Muslims, Baptists, Scientologists and Raelians who take their bullshit too far are all rounded up and given lethal injections. Anyone who even vaguely shows promise of turning a new leaf and subscribing to a more moderate version of their initial faith is spared.
Oh, and Creationism would be banned. God created dinosaurs? Foolish theist, to the Greenhouse Gulag! Go and spend the rest of your life tending hydroponically produced fruits and vegetables to feed the Third World and be condemned to enjoy a steady diet of Stephen Hawking, Carl Sagan and Bill Maher videos, along with classes in critical thinking!
It isn't terribly evil, I know - but hey. This is Real Life, I don't have it in me to reason like Pigface Ganon, from the eighties' Legend of Zelda cartoon.
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"I'm evil and I need no justification or reason for it because I'm evil! MUAHAHAHAHAHAHA!"